Mô phỏng công nghệ hóa học và dầu khí - Unit 7: Compressor

Nhóm Mô phỏng Công nghệ Hoá học và Dầu khí Trường Đại học Bách khoa Hà Nội Dynamic Modeling using UniSim Design Unit 7 Compressor Learning Objectives  Specify Head and Efficiency curves to compressors  Use multiple curves to model compressors  Make changes/additions to the dynamic model  Move pressure-flow specs around  Accurately model existing plant equipment using Unisim Design 2 Contents  Add the compressor  Surge and Stonewall curves of compressor  Compressor Surge Control Head = A + BQ + CQ2 + DQ3  Caculated value A,B,C,D  Advanced Modeling - Pipe Segment 3 Add the Compressor  Open 06.AC Pump HEX.usc  Open 07.Compressor Curves.xls  Press button GO on the Compressor Curve Data → automatically create Compressor on the Flowsheet Set the Compressor Curve information 4 Add the Compressor 5 Press GO Add the Compressor  Rating tab → Curve page  Connect the streams to Compressor: Inlet Stream: KO Vap Oulet stream: Comp Out Enery stream: q-Comp  Rating tab → Curve page: check activate box to each curve  Dynamic tab → Specs page: Uncheck Duty and Polytropic Efficiency Check Speed and Use Characteristic Curves  Speed 5000 rpm. → Run Integrator 6 Add the Compressor 7 6 Add the Compressor 8 uncheck Check 5000 check Add the Compressor  Set P-specs with stream Comp Out, set it to 8000 kPa. Start Integrator a few minute  Add a discharge valve Comp Valve:  Inlet stream: Comp Out  Outlet stream: 5  P-Specs: Remove P-specs of stream KO-Vap Check P-specs of stream 5. Set it to 6900 kPa 9 Add the Compressor  Change the Valve Manufacturers to Universal Gas Sizing and Size valve  Add a PC-KO to control the Compressor  Use the Pressure recorded at the end of step 8 as the Set Point  Start Integrator a few minutes and observe 10 Add the Compressor In this cell Enter Connections Name PC-KO Process Variable Source Comp Out – Pressure Output Target variable Comp Valve – Actuator Desired Position Parameters Action Direct Range PV Minimum 6000 kPa Range PV Maximum 10500 kPa 11 Add an Anti-Surge Line  Add a valve to the simualation and make sure the Valve Opening is 0%. The name valve is Anti-Surge Valve  Size the Cg of new valve value 10% of Comp valve.  Dynamic tab → Specs page: Press Surge Controller button of compressor 12 Add an Anti-Surge Line  The output of Surge Controller is the Anti-Surge Valve  Disconnect the compressor discharge stream form the inlet of the compressor discharge valve Comp Valve  Add Tee with: Inlet: Comp Out Outlet: Comp Valve and anti-surge Valve 13 Add an Anti-Surge Line 14 Add an Anti-Surge Line 15 Add an Anti-Surge Line  Comp Valve: Inlet: 6 Outlet: to To pipe  Anti-surge Valve: Inlet: 7 Outlet: 8 (to the Knockout Drum)  Save case 07.Comp.usc 16 Calculate Surge Controller  Surge Controller is used exclusively for Compressors  In Automatic Mod: SP is calculated by the controller itself, it is not set by user  Surge line for the compressor model is entered as a speed vs. flow rate curve in a tabular form 17 Calculate Surge Controller  For the purpose of the surge controller, the surge line is calculated from the formula: Head = A + BQ + CQ2 + DQ3 Head = compressor calculated head (m) Q = surge flow rate (m3/s) A, B, C, D = paremeter specified by the user  We can caculate both A, B, C and D but simplify, set B and D zero, A[m], C[s2/m6] 18 Calculate A, B, C, D Speed (rpm)s Head (m) Min Vol Flow (m3/h) Mon Vol Flow (m3/s) Vol Flow Squared (m6/s2) 2488 665,14227 3373,9148 0,937198556 0,878341133 3733 1540,3053 5060,8722 1,405797833 1,976267548 4977 2810,1577 6913,6994 1,920472056 3,688212916 6177 4460,9873 8635,6414 2,398789278 5,754189999  Looking at the Compressor Curves, enter in the cells: 19 Calculate A, B (C&D=0) y = 774.93x - 13.181 R² = 0.9998 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 1 2 3 4 5 6 7 A xi s Ti tl e Axis Title Comp Comp A = -13.181 B = 774.93 20 Control Line  Control Line is the primary Set Point for the Controller 𝑄 = 100 + 𝑋 100 𝑄𝑆𝑢𝑟𝑔𝑒 Q = Control Flow Rate[m3/s] X = Control Line % (Specified in the Controller) Qsurge = Surge Flow [m 3/s]  Control Line is set at some % (typically 10%)  Controller tries to maintain the compressor flow above 21 Backup Line  Backup Line: are located between Surge Line and Control Line  Flow is above BL → PID algorithm is used  Flow drops below BL→take to prevent surge  BL flow rate typically 5%  Recycle Valve: Quick Opening rate 3%/s  Save as 07.Comp.usc 22 Surge Controller 23 A= -13.1808 C= 774.929 B = 0 D = 0 Surge Controller  Parameters tab 24 Min = 0 m3/h Max=14160 m3/h Add Spreadsheet  Calculate the Surge Flow: 𝑄𝑆𝑢𝑟𝑔𝑒 = 𝐻𝑒𝑎𝑑 𝑚 −𝐴 𝐶 [m3/sec]  Head: imported from Compressor  A&C: imported from Surge Controller 25 Add Spreadsheet  Formula:  Save case as 07.Comp1.usc 26 Surge Flow Rate = sqrt((b5-b1)/b2)*3600 Control Flow Rate = b7*1.1 Backup Flow Rate = b7*1.05 Add Spreadsheet 27 Add Spreadsheet 28 Add a Pipe Segment  Select pipe segment from object palette  Inlet stream: To Pipe  Outlet stream: 5  Rating tab → Sizing page of the pipe specify the following: 29 Add a Pipe Segment In this Cell Enter Connections Name Pipe-100 Parameters Fitting or Pipe Pipe Length 200 m Pipe Schedule Schedule 80 Pipe Material Mild Steel Pipe Nominal Diameter 355.6 mm (14 in) 30 Add a Pipe Segment 31 Add a Pipe Segment 32 Add a Pipe Segment 33 Add a Pipe Segment  Dynamics tab → Parameters page: select the Pipe Model Correlation option  Leave the other option at the default values  Move the P-specs to the stream 5 and set pressure is 6640 kPa  Start Integrator and run the model Observe a few minutes.  Save case 07.CompE.usc 34